Toggle switch with shock absorber



July 9, 1957 G. R. LAWSON ET AL TOGGLE SWITCH WITH SHOCK ABSORBER FiledJuly 31, 1956 [hwy/#0123: 605/5)" Elsa/sol? Gav/ye .5 59/76/70?! y W K m7Ze/r fi'ffamqg Unite Our invention relates to an electric switch andparticularly to the type of electric switch known as a toggle switchhaving an over-center spring member for giving the switch a snap action.

A toggle switch of the class described has a hollow housing comprising arecessed base of insulating material and a cover member. In a singlepole toggle switch a pair of fixed contacts are arranged near one end ofthe base and each adjacent one of the opposite side walls, while thereis an oscillating flapper pivotally mounted by means of trunnions fromthe side walls of the base to form a movable contact which bridges thecircuit between the fixed contacts. As is the usual practice, anovercenter coil spring is supported on the flapper and compressedbetween the flapper and the bottom portion of a switch trigger that isalso pivotally mounted from the base. The trigger has two extremepositions and when it is moved from one to the other position, it firstcompresses the spring which expands and forces the flapper to swing toits opposite position. When this takes place, the spring tends to rockfrom one side of the flapper to the other, and once it passes throughthe plane of the flapper it is no longer compressed and it tends toexpand rapidly to move the flapper to its other extreme position.Finally, in the closed circuit position the flapper is wedged betweenthe pair of fixed contacts.

.In all of the known prior art devices, a vertical stop member is moldedin the base of the switch and serves to bring the flapper to a suddenhalt at the end of its stroke. However, in these prior art devices,serious damage may be caused by the electrical arcs which are struckduring the opening and closing of the switch mechanism. This damage isdue to the extreme temperatures attained which tend to weld the contactstogether and carbonize the switch housing. Also, failures have occurreddue to the fact that the flapper has bounced out of the fixed contacts,or the fixed contacts vibrate with respect to the flapper therebydrawing high current arcs which melt the two contactsurfaces to causethe welding of the contacts when they reclose.

This situation has been successfully met by the present invention wherethe mechanical action of the mechanism has been stabilized in thepreferred embodiment by using stop members inclined appr ximately 15from the vertical so that the relative angle between the plane of theflapper and the stop when the two are in engagement is less than 90.Thus, When the flapper strikes the stop member the flapper will tend toclimb up the inclined surface thereby compressing the spring and raisingthe trunnions of the flapper out of their open bearings to absorb theshock of the rapidly moving flapper. It is not the friction between theflapper and the inclined stop which provides this improved result, butit is the shock absorbing action caused by the direction of the force ofthe spring which does not take eifect until after the normal travel ofthe flapper is over and which adjusts its own eifectiveness to theamount of excess energy to be absorbed. After this action is completed,the flapper returns to its normal rest position which is a predeterminedpoint. It will thus be seen that the presence of a shock absorbingfeature has no adverse eifect on the next cycle of operation.

This invention results in several important results, namely, it makespossible the use of a higher speed for the flapper and greater forcesthan were used previously States Patent because of the rebound problem.This higher speed results in faster breaking of the circuit andconsequent arc extinction. Also, the higher forces permit greatercontact pressure with less bounce.

Accordingly, the principal object of this invention is to provide anelectrical toggle switch with a shock absorbing feature to prevent theoscillating flapper from bouncing out from between the fixed contactswhen the switch is being closed.

A further object of this invention is to provide an electrical toggleswitch with a shock absorbing feature for the oscillating flapper sothat the flapper speed may be increased which will in turn permit ahigher fixed contact spring pressure.

A further object of this invention is to provide an elec' tric switchwith an inclined stop member between the fixed contacts of the switch toabsorb the shock of the movable contact as it is brought into engagementwith the fixed contacts.

A further object of this invention is to decrease the damage due to theburning of the contacts by the electrical are by stabilizing themechanical action of the switch with an inclined stop member that willabsorb the shock of the flapper striking the stop when taking advantageof the over-center spring of the switch to perform the additionalfunction of arresting the motion of the flapper.

Our invention will be better understood from the fol lowing descriptiontaken in connection with the accompanying drawing and its scope will bepointed out in the appended claims.

Fig. 1 is a front elevational view of a toggle switch embodying ourinvention.

Fig. 2 is a cross-sectional elevation view taken along the central planeof the switch and showing the mechanism of the switch in the offposition.

Fig. 3 is a top plan view of the recessed base of the switch merelyshowing the fixed contacts of the switch inserted therein as well as theinclined stop members for cooperation with the oscillating flapper thatis not shown in this view.

Fig. 4 is a cross-sectional elevational view similar to that of Fig. 2except that the trigger has been moved to its opposite position and theflapper is shown instantaneously rising up the inclined stop memberagainst the compressive action of the over-center spring.

Fig. 5 is an exploded view of the switch parts which are included in oneembodiment of our invention.

Referring in detail to the drawing and in particular to Fig. 1, 10represents a hollow switch housing comprising a recessed base 11 moldedof suitable insulating material and a metal mounting strap 12 whichserves as a cover for the base as well as the means for supporting theswitch in a switch box as will be well understood by those skilled inthis art. A switch handle or trigger 13 is likewise a molded part ofinsulating material and it is pivotally mounted in open bearings in theopposite side walls of the base for movement between its two extremepositions.

A better understanding of the design of the parts of this switch may behad by considering the exploded view of Fig. 5 showing a single poleswitch embodying our invention. The recessed base 11 is generally of boxshape with an open top 14 that is closed by a mounting strap 12 when theswitch is fully assembled. Open windows 15 are cut at one end of thebase in the opposite side walls 16 and 17. The side faces 18 of thewindows 15 are grooved to receive the side edges of the terminalportions 19 of a pair of fixed contacts 20. The lower portion 21 of eachfixed contact is offset inwardly from the terminal portion 19 to lieagainst the interior surface of the respective side walls 16 and 17. Aterminal screw 22 is .located in a threaded opening 23 in each terminal1.9 so that lead .wires may connec ed .to the fixed .contacts and theswitch joined into the electrical circuit that is to be controlled.

The movable contac of th switch is rep esente .by a pe fl pper 25 havin,opposite ydi po ed runnions 26 arranged near the tops of its uprightportions to be supported in open bearings 27 in the sidewalls 16 and 17of ,the switch base. The ,flapper is ,adapted to oscillate fr m a pionco necting the .two fixed contacts .to an opposite position where,the switch holds the circuit open. The molded switch :handle or triggerhas a similar set of trunnions 31 arranged near its bottom to seat in,the open bearings 32in 'the side walls of the baseslightly above andoutside the previously mentioned open bearings 27. Extending,.downwardly trom the bottom .of the trigger .-is acentralprojection 33Whichserves as a spring seat for an over-center spring 351 ofthe togglemechanism. Finally, apair of rigid fingers 3.5 aredisposed below eachtrunnion 3,1 ;for engagement with the upper ends ,of the uprights of theflapper 2 when the trigger is beingshifted to its opposite position.These fingers 35 constitute a positive kickofl ,feature to insure thatthe flapper .will move when the ,handle is shifted. The best showing ofthis is probably ;in Fig. 2 although it should be recognized that thisfeature is ,welhknown in,the art and does not constitute partof thepresentin- Vention.

A second spring seat 36 for supporting the lower end .of the over-centerspring 34 is disposed in the base of the U-shaped flapper 25 so that thespring may rock in the plane of movementvof theswitch trigger 13. Theassembly of the switch is completed by a U -shaped insulating plate 37whichis sandwiched between the mounting strap 12 and the top of the base11 at the end nearest the fixed contacts 20 so as to insulate .the fixedcontacts from each other. The mountingstrap .12 is of conventionalconstruction which ,is stamped ,out of thin sheet steel material,andvhas a pairof {IT-shaped lanced members 38 at the ends which arebent .down around the ends .of the base v11 to be engaged under theledges .39 .in a ,welhknown manner.

The construction oftheswitch as explained above .is generallyconventional design .which necessitated .the ,introduction of thepresent invention. Figs. 2, ,3, and 4 show the:base.-11 with a pair.ofbackwardly inclinedistop members dtlone of which:is.disposed between.the fixed contacts 29. The angle of inclination :is suchnthat theincluded angle between .the .flapper ,when it is. in engagement with.the stop is;less .than 90. Thus, it .will be seen thatasltheflapperfirst engages the stop, the flapper will be moving atss'ucha.speed that:it.will tend to climb upthe inclination. .This riseistresisted=by the compression of the over-center spring -3.4 .as thetrunnions of the flapper are lifted outofthe' openbearingsifl. Hence,.the over-centerspring performstwo functions. .First, it .provides thenecessaryt'oggleIaction for the quick openingand closingof theswitchand, second it serves the oppositefunction of slowing down andstopping the movement of the flapper when it reaches the end of itsstroke. This unobviousresult hasbeenaccomplished by utilizing theelements already presentin the combination rather than an increase inthe number of switch parts.

Having described above-ourinvention as it is used 'in a single poletoggle action switch, it will be readily appreciated that while ourinvention is relatively simple in nature and easy to-apply to existingdesigns, it has brought .about .a noteworthy increase ,in the efliciency..and..reliability of toggle v.actionswitches .and represents .adecided. advancein this art. These .problemshave existed.in. this artsincethe .advenLofi toggle switches. nearly -5.0 years. ago yetithas.not.been. untilthis late. date, that 'this invention hasbeenmadetoimprove the operation at these switches. Modifications .ofthis invention will occur to those skilled in this ant and it is to beunderstood, therefore, that this .iflXQIltiQl i no limi ed to theparticu a embodimen .siisclosed but that it is intended to cover allmodifications which are within the true spirit and scope of thisinvention.

1, at we claim as new and desire to secure by Letters Patent of theUnited States is:

1. A snap action switch comprising a hollow housing having a recessedbase and a cover member, fixed contacts arranged in the base, and aU-shaped flapper provided with trunnions journaled in open hearings inopposite side walls of the recessed base, the flapper serving asthemovable contact of'the switch to bridge the circuit between the fixedcontacts, a switch trigger also having trunnions pivotally supportedfrom the side walls of the base parallel to the pivotal axis of theflapper, an upwardly facing spring seat on the lower portion of theflapper, and a downwardly facing spring seat on the lower portion of thetrigger, a coil spring compressed between the complementary'spring seatsof thetrigger and flapper, the invention comprising abackwardly'incline'd wall formed in the base between the fixed contactsso that 'the'motion of the flapper will be arrested when the flapperstrikes the inclined wall and tends to climb over it 'ther'eby'moving:the flapper upwardly out of its bearings fagains't theresistanceof the spring. 2." An electrical switch comprising a hollowhousing having a fixe d' contact -arranged adjacent two of the op"-posite sidewalls thereof, and a U-shaped flapper provided with trunnions journaled in over-sized bearings in the said opposite side walls ofthe housing, the flapper serving as the movable contact of the switch tobridge the g'apbetw'een the fixed contacts, a switch trigger alsotrunnionspivot ally' supported from the said'side wall s'of the housingwith a pivotal axis parallel tothe pivotal axis of the flapper, and anover-center spring compressed between the lower portion of'the triggerand the bottom portion ofthe flappenthe invention comprising abackwardly inclined wall formed in the base between the fixed contactsso that the motion of the flapper "will be arrested when the flapperstrikes the inclined wall :and tends to :climb over it, thereby movingthe flapper upwardly out of its bearings against the resistance of'thespring the relative angle betweenthe plane of the flapper and theinclined wall when the flapper is engagingjthe wall being'less than 3. Asnap action toggle switch comprising a hollow housing formed by arecessed base of insulating material and a cover member, at leasttwofixed contacts supported atone end of the base adjacent the oppositeside walls thereof, and a U-shaped flapper provided with trunnions atits upper portion which are journaled inopen' bearings 'in thesaidopposite side walls of the base, the flapper serving as the movablecontact of .the switch to close the'circuit between the fixed contacts,aswitch trigger Lpivotally mounted inthe base with thepivotal axisparallel to the p-ivotal axis of the flapper, and spring 'meansfconnectedbetween the lower portion ofthe trigger and ithe lowerQportionof the flapper for providing the flap- :per with ,a snap action, and abackwardlyinclined .wall Ifo'rmedin the base between the fixed contactsfor arrest- .ing' the,motion of the flapper as it nears the endof itsstroke when the flapper tends torise up the inclined sur- .face and moveout of its supporting bearings against the .r'esistance ofthe spring,the relative angle between the .plane of the flapper andthe inclinedwall being less than Q9O.

References Cited in theme of this patent

